In communication systems approved by the Third Generation Partnership Project (3GPP), such as Wideband Code Division Multiple Access (WCDMA: a registered trademark), Long Term Evolution (LTE), and LTE-Advanced (LTE-A), or in communication systems approved by the Institute of Electrical and Electronics Engineers (IEEE), such as Wireless Local Area Network (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX), a base station apparatus (a cell, a first communication apparatus (a communication apparatus that is different from a terminal device), or an eNodeB) and a terminal device (a mobile terminal, a mobile station apparatus, a second communication device (a communication device that is different from the base station apparatus), user equipment (UE), a user device) each include multiple transmit and receive antennas, and, by using a Multi Input Multi Output (MIMO) technology, space-multiplex a data signal and realize high-speed data communication.
Furthermore, in 3GPP, in order to realize high-speed data communication between the base station apparatus and the terminal device, carrier aggregation (CA) in which the communication is performed at the same time using multiple component carriers is employed (NPL 1).
In 3GPP, as a frame structure type in compliance with a bidirectional communication scheme, Frequency Division Duplex (FDD) and Time Division Duplex (TDD) are employed. Furthermore, in FDD, a full duplex scheme in which bidirectional communication is possible at the same time and a half duplex scheme in which the bidirectional communication is realized by switching from one direction communication to another direction communication (NPL 2) are employed. Moreover, in some cases, LTE in which TDD is employed is referred to as TD-LTE or LTE TDD.
Furthermore, in 3GPP, TDD-FDD carrier aggregation (TDD-FDD CA) is considered in which a component carrier (TDD carrier) that supports TDD and a component carrier (FDD carrier) that supports FDD are aggregated and communication is performed (NPL 3).